Conventionally, as a drive unit, a drive unit is known that moves a driven object such as a heavy object by using a pair of interlocking chains, which are also referred to as zip chains. Specifically, the pair of interlocking chains are interlocked with each other and integrally driven (for example, refer to Patent Document 1).
Also, a silent chain transmission device has known in which noise and vibrations caused in driving of chains are suppressed by defining shapes of faces of link plates to be interlocked with inner flanks, i.e., sprocket teeth (for example, refer to Patent Document 2).